Methane has previously been chlorinated with gaseous chlorine or subjected to oxychlorination with oxygen and hydrochloric acid to form methyl chloride together with other chlorides, such as dichloromethane, trichloromethane and carbon tetrachloride. In the halogenation of methane by either method, hydrochloric acid is produced. Such hydrochloric acid must be recovered, dehydrated by azeotropic distillation and recycled.
Reduced chloromethanes are then hydrolyzed in vapor phase to methanol, formaldehyde, formic acid, carbon dioxide and hydrochloric acid. Resulting compositions depend on the chlorination selectivity to methyl chloride and to other chlorides. Corrosion and problems involved with handling chlorine and hydrochloric acid are substantial.